This invention relates to a device for automatically stopping and restarting an engine.
Tokkai 2000-274273 published by the Japanese Patent Office in 2000 discloses a device for automatically stopping an engine to conserve fuel when a vehicle has temporarily stopped, and automatically restarting when the driver steps on the accelerator pedal, while traveling and in the state where a transmission remains in a drive range.
In a vehicle equipped with an automatic stop/restart device of this type, the engine is restarted based on the command of a control unit, and it is possible that the engine will be restarted unintentionally by the driver, for example, when the battery voltage drops. If the brake pedal is not depressed when this automatic restart is performed, the vehicle moves although unintended by the driver.
It is therefore an object of this invention to prevent a vehicle moving when the engine is restarted based on the command of the control unit which is not based on the driver""s intention, in a vehicle provided with the automatic stop/restart device which is capable of performing automatic stop/restart in a drive range.
In order to achieve above object, this invention provides an automatic stop/restart device for an engine of a vehicle, the vehicle comprising a drive wheel, an accelerator pedal, a brake pedal, a battery, and a motive force transmission mechanism which transmits a creep force to the drive wheel according to the rotation of an engine.
The automatic stop/restart device comprises a motor which starts the engine, a sensor which detects if the transmission mechanism is in a drive range wherein the creep force is transmitted to the drive wheel, a sensor which detects that the brake pedal is depressed, a sensor which detects that the accelerator pedal is depressed, a sensor which detects a state of charge (SOC) of the battery, a sensor which detects a depression amount of the brake pedal, and a microprocessor.
The microprocessor is programmed to stop the rotation of the engine when the brake pedal is depressed and the vehicle is stationary, determine if the vehicle is in an idling stop state wherein the brake pedal is depressed, the vehicle is stationary with the engine stopped and the transmission mechanism is in the drive range, restart the engine by the motor when the accelerator pedal is depressed or the battery SOC has fallen below a predetermined SOC in the idling stop state, and restart the engine by the motor when the brake pedal depression amount has decreased by a predetermined amount in the idling stop state.
The details as well as other features and advantages of this invention are set forth in the remainder of the specification and are shown in the accompanying drawings.